240 British Dragoiiflics 



segments ; on segment i the spot is squarish, with pro- 

 jections at the anterior corners ; on 2 to 5 a longitudinal 

 rectangular spot, with a projection on each side near the 

 distal end ; often these spots almost or entirely disappear, 

 the projections being the last to go, but that on 2 does 

 not go so readil}^ as the others ; specimens are found at 

 all intermediate stages. On 6 a mid-dorsal spot, in- 

 creasing in width from the base ; on 7 to 10 the black 

 spot almost fills each segment ; the dorsal carina is 

 sometimes blue on most segments, and is generall}' so on 

 6, 7, and 8, and it swells into a spot on 9 and 10 ; there 

 are also some small lateral black spots. A^ial appendages, 

 upper triangular, blue ; lower cylindrical, blue at base, 

 then produced into a sharp black incurved point. 



Female Imag"o. 



Stouter than male, which, however, it resembles in 

 most respects. The blue gives place to yellow with a 

 greenish tinge. Pterostignia yellow. Tenth segment of 

 abdomen unspotted, and ninth nearly so. Anal 

 appendages triangular, short, greenish-yellow. Ovipositor 

 reddish, slender, sharp, curved upwards at tip, as long 

 as the ninth segment. ]'alvcs a little longer, }-ello\vish. 



Variation. 



In the description of the male the great variation 

 in the dorsal spots has been referred to. When the 

 carina is of the ground-colour, the spots appear as two 

 parallel lines ; it is this form apparently that De Sel>-s 

 names var. bilineata. This Dragonfly \^aries also in the 

 ground-colour, which is sometimes white or whitish, the 

 spots being reduced at the same time. This form has 



